Some micro organism can set off unexploded viral grenades in neighboring micro organism’s DNA.
Certain Escherichia coli micro organism, together with some that stay in human intestines, make a chemical known as colibactin. That chemical awakens dormant viruses inside close by micro organism, typically resulting in their destruction, researchers report February 23 in Nature.
This sort of organic warfare amongst micro organism hasn’t been described earlier than. “It’s an interesting strategy, and it’s also a dangerous strategy,” says Heather Hendrickson, an evolutionary microbiologist on the University of Canterbury in Christchurch, New Zealand, who was not concerned within the work.
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Colibactin producers should creep up on their bacterial enemies and set off the unexploded ordinance hiding within the enemies’ DNA. Those grenades are prophages — bacteria-infecting viruses which have inserted themselves into their hosts’ DNA, the place they disguise out innocent and dormant till one thing triggers their awakening. That one thing, on this case, is DNA injury attributable to colibactin.
When colibactin dings DNA, a bacterial restore system known as the SOS response kicks in, chemical biologist Emily Balskus and colleagues discovered. “What many phages have done is to tap into that response,” says Balskus, a Howard Hughes Medical Institute investigator at Harvard University.
“It’s a signal for them to move out of this dormant lifestyle and awaken to kill their host and move on to find a new host,” she says. Once phages get up, they replicate and burst out of the host cell, destroying it.
But as soon as these viral grenades go off, they will infect different micro organism, doubtlessly exposing the attacking micro organism and different close-by microbes to organic shrapnel.
Humans may additionally get caught within the cross fireplace. Researchers already knew that colibactin may cause injury to human DNA that will result in colon most cancers. But why the micro organism would use the chemical in opposition to individuals wasn’t recognized.
The new analysis means that E. coli might not be producing colibactin to assault its human hosts, however as a countermeasure in opposition to different microbes, Hendrickson says (SN: 12/14/21). “It’s easy to forget that there’s this continual conversation and warfare going on between bacteria, and we might not be the focus of their activities.”
Among micro organism, colibactin isn’t normally a deadly weapon. In most micro organism that Balskus and her colleagues examined, colibactin prompted DNA injury, however the micro organism had been in a position to restore the injuries. That could also be as a result of colibactin is an unstable chemical that shortly degrades earlier than it will possibly break sufficient DNA to do irreparable hurt, Balskus says. Some micro organism additionally make different chemical compounds that defuse colibactin earlier than it will possibly injury DNA, her staff discovered. Only micro organism which have unexploded prophages of their DNA and no different defenses had been weak to colibactin-producing micro organism in laboratory dishes.
Because colibactin decays shortly, “it suggests this is a very short-range communication,” says Michael Dougherty, a microbiome researcher on the University of Florida in Gainesville who was not concerned within the examine. “Maybe it could have an effect when bacteria are forming biofilms where you have trillions of bacteria stacked on top of each other.”
Colibactin might not be the one issue concerned in exploding neighboring micro organism, says Dougherty’s University of Florida colleague Christian Jobin. Balskus’ staff didn’t exhibit that colibactin alone might detonate prophages. Perhaps one thing else in regards to the colibactin-producing bacterium’s presence is required to kick off the fireworks, he suggests.
The researchers don’t but know whether or not colibactin can set off prophages when micro organism are of their pure habitats, akin to human and different animal intestines. And maybe awakening the viruses is an accident, Balskus speculates.
“Maybe [colibactin] didn’t really evolve to kill. Maybe its primary ecological function involves doing something else,” she says. What that is perhaps is a thriller that Balskus and her colleagues are working to unravel.